AT-40
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
●: Solenoid ON
×: Solenoid OFF
–: Non-standard condition
Line Pressure Solenoid Valve
If non-standard solenoid signal is sent to TCM, line pressure solenoid valve is turned OFF to achieve maxi-
mum oil pressure.
Torque Converter Clutch Solenoid Valve
If non-standard solenoid signal is sent to TCM, torque converter clutch solenoid valve is turned OFF to release
lock-up.
Overrun Clutch Solenoid Valve
If non-standard solenoid signal is sent to TCM, overrun clutch solenoid valve is turned OFF to engage overrun
clutch. This will result in more effective engine brake during deceleration.
How to Perform Trouble Diagnosis for Quick and Accurate RepairINFOID:0000000001703179
INTRODUCTION
The TCM receives a signal from the vehicle speed sensor, accelera-
tor pedal position sensor or PNP switch and provides shift control or
lock-up control via A/T solenoid valves.
The TCM also communicates with the ECM by means of a signal
sent from sensing elements used with the OBD-related parts of the
A/T system for malfunction-diagnostic purposes. The TCM is capa-
ble of diagnosing malfunctioning parts while the ECM can store mal-
functions in its memory.
Input and output signals must always be correct and stable in the
operation of the A/T system. The A/T system must be in good oper-
ating condition and be free of valve seizure, solenoid valve malfunc-
tion, etc.
It is much more difficult to diagnose a malfunction that occurs intermittently rather than continuously. Most
intermittent malfunctions are caused by poor electric connections or improper wiring. In this case, careful
checking of suspected circuits may help prevent the replacement of good parts.
Shift positionNormalMalfunction in solenoid
valve AMalfunction in solenoid
valve BMalfunction in solenoid
valves A and B
A B Gear A B Gear A B Gear A B Gear
“D” position●●1st –●→×
3rd ●→×–
3rd ––
3rd ×●2nd –●→× ×–––
××3rd – x×–––
●×4th – x●→×–––
“2” position●●1st –●→×●→×–––
×●2nd –●→× ×–––
××3rd – x×–––
“1” position●●1st –●→×●→×–––
×●2nd –●→× ×–––
××3rd – x×–––
SAT631IA
TROUBLE DIAGNOSIS
AT-41
< SERVICE INFORMATION >
D
E
F
G
H
I
J
K
L
MA
B
AT
N
O
P
A visual check only, may not find the cause of the malfunctions. A
road test with CONSULT-III or a circuit tester connected should be
performed. Follow the "WORK FLOW" .
Before undertaking actual checks, take a few minutes to talk with a
customer who approaches with a driveability complaint. The cus-
tomer can supply good information about such malfunctions, espe-
cially intermittent ones. Find out what symptoms are present and
under what conditions they occur. A “DIAGNOSTIC WORKSHEET”
like the example ("DIAGNOSTIC WORKSHEET" ) should be used.
Start your diagnosis by looking for “conventional” malfunctions first.
This will help troubleshoot driveability malfunctions on an electroni-
cally controlled engine vehicle.
Also check related Service bulletins for information.
WORK FLOW
A good understanding of the malfunction conditions can make troubleshooting faster and more accurate. In
general, each customer feels differently about a malfunction. It is important to fully understand the symptoms
or conditions for a customer complaint.
Make good use of the two sheets provided, "Information from customer" and "Diagnostic Worksheet Chart" ,
to perform the best troubleshooting possible.
Work Flow Chart
SAT632I
SEF234G
TROUBLE DIAGNOSIS
AT-43
< SERVICE INFORMATION >
D
E
F
G
H
I
J
K
L
MA
B
AT
N
O
P Diagnostic Worksheet Chart
Customer name MR./MS Model & Year VIN
Trans. model Engine Mileage
Incident Date Manuf. Date In Service Date
Frequency❏ Continuous❏ Intermittent ( times a day)
Symptoms❏ Vehicle does not move. (❏ Any position❏ Particular position)
❏ No up-shift (❏ 1st → 2nd❏ 2nd → 3rd❏ 3rd → 4th)
❏ No down-shift (❏ 4th → 3rd❏ 3rd → 2nd❏ 2nd → 1st)
❏ Lock-up malfunction
❏ Shift point too high or too low.
❏ Shift shock or slip (❏ N → D❏ Lock-up❏ Any drive position)
❏ Noise or vibration
❏ No kick down
❏ No pattern select
❏ Others
()
Malfunction indicator lamp (MIL)❏ Continuously lit❏ Not lit
1.❏ Read the Fail-safe and listen to customer complaints.AT- 3 9,
"Information
from custom-
er"
2.❏ Check A/T fluidMA-22
❏ Leakage (Follow specified procedure)
❏ Fluid condition
❏ Fluid level
3.❏ Perform “STALL TEST” and “LINE PRESSURE TEST”.AT- 4 8
,
AT- 4 8
❏“STALL TEST”— Mark possible damaged components/others.
❏ Torque converter one-way clutch
❏ Reverse clutch
❏ Forward clutch
❏ Overrun clutch
❏ Forward one-way clutch❏ Low & reverse brake
❏ Low one-way clutch
❏ Engine
❏ Line pressure is low
❏ Clutches and brakes except high clutch and
brake band are OK
❏“LINE PRESSURE TEST”— Suspected parts:
AT-44
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
4.❏ Perform “Road Test”.AT- 5 2
4-1. “Check Before Engine is Started”AT- 5 3
❏AT- 1 7 6 , "OD OFF Indicator Lamp Does Not Come On"
❏ Perform self-diagnosis. Enter checks for detected items. AT- 7 3 , AT- 7 8 .
❏AT- 8 3
.
❏AT- 8 6
.
❏AT- 9 1
.
❏AT- 9 6
.
❏AT- 1 0 1
.
❏AT- 1 0 5
❏AT- 1 0 8 .
❏AT- 111
.
❏AT- 11 4
.
❏AT- 11 9
.
❏AT- 1 2 4
.
❏AT- 1 2 9
.
❏AT- 1 3 4
.
❏AT- 1 3 9
.
❏AT- 1 4 4
.
❏AT- 1 4 9
.
❏AT- 1 5 2
.
❏AT- 1 5 8
.
❏AT- 1 6 3
.
❏AT- 1 6 4
.
4-2. “Check at Idle”AT- 5 3
❏AT- 1 7 8 , "Engine Cannot Be Started in "P" and "N" Position" .
❏AT- 1 7 9 , "
In "P" Position, Vehicle Moves Forward or Backward When Pushed" .
❏AT- 1 7 9 , "
In "N" Position, Vehicle Moves" .
❏AT- 1 8 0 , "
Large Shock "N" → "R" Position" .
❏AT- 1 8 1 , "
Vehicle Does Not Creep Backward in "R" Position" .
❏AT- 1 8 2 , "
Vehicle Does Not Creep Forward in "D", "2" or "1" Position" .
TROUBLE DIAGNOSIS
AT-45
< SERVICE INFORMATION >
D
E
F
G
H
I
J
K
L
MA
B
AT
N
O
P
4. 4-3. “Cruise Test”AT- 5 5
Part 1
❏AT- 1 8 3 , "
Vehicle Cannot Be Started from D1" .
❏AT- 1 8 5 , "
A/T Does Not Shift: D1→ D2or Does Not Kickdown: D4→ D2" .
❏AT- 1 8 6 , "
A/T Does Not Shift: D2→ D3" .
❏AT- 1 8 8 , "
A/T Does Not Shift: D3→ D4" .
❏AT- 1 8 9 , "
A/T Does Not Perform Lock-up" .
❏AT- 1 9 0 , "
A/T Does Not Hold Lock-up Condition" .
❏AT- 1 9 1 , "
Lock-up Is Not Released" .
❏AT- 1 9 2 , "
Engine Speed Does Not Return to Idle (Light Braking D4→ D3)" .
Part 2AT- 5 8
❏AT- 1 8 3 , "Vehicle Cannot Be Started from D1" .
❏AT- 1 8 5 , "
A/T Does Not Shift: D1→ D2or Does Not Kickdown: D4→ D2" .
❏AT- 1 8 6 , "
A/T Does Not Shift: D2→ D3" .
❏AT- 1 8 8 , "
A/T Does Not Shift: D3→ D4" .
Part 3AT- 5 9
❏AT- 1 9 3 , "A/T Does Not Shift: D4→ D3, When OD OFF" .
❏AT- 1 9 4 , "
A/T Does Not Shift: D3→ 22, When Selector Lever "D" → "2" Position" .
❏AT- 1 9 5 , "
A/T Does Not Shift: 22→ 11, When Selector Lever "2" → "1" Position" .
❏AT- 1 9 7 , "
Vehicle Does Not Decelerate by Engine Brake" .
❏ Perform self-diagnosis. Enter checks for detected items. AT- 7 3
, AT- 7 8 .
❏AT- 8 3
.
❏AT- 8 6
.
❏AT- 9 1
.
❏AT- 9 6
.
❏AT- 1 0 1
.
❏AT- 1 0 5
❏AT- 1 0 8 .
❏AT- 111
.
❏AT- 11 4
.
❏AT- 11 9
.
❏AT- 1 2 4
.
❏AT- 1 2 9
.
❏AT- 1 3 4
.
❏AT- 1 3 9
.
❏AT- 1 4 4
.
❏AT- 1 4 9
.
❏AT- 1 5 2
.
❏AT- 1 5 8
.
❏AT- 1 6 3
.
❏AT- 1 6 4
.
5.❏ For self-diagnosis NG items, inspect each component. Repair or replace the damaged parts.AT- 7 3
,
AT- 7 8
6.❏ Perform “Road Test”.AT- 5 2
7.❏ Perform the Diagnostic Procedures for all remaining items marked NG. Repair or replace the damaged parts.
Refer to the Symptom Chart when you perform the procedures. (The chart also shows some other possible symp-
toms and the component inspection orders.)AT- 6 1
8.❏ Erase DTC from TCM and ECM memories.AT- 3 6,
AT- 7 8
AT-48
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
Inspections Before Trouble Diagnosis
INFOID:0000000001703182
A/T FLUID CHECK
Fluid Leakage and Fluid Level Check
Check fluid leakage and check the fluid level. Refer to MA-22, "Checking A/T Fluid".
Fluid Condition Check
Check the A/T fluid condition.
STALL TEST
Stall Test Procedure
1. Check ATF and engine oil levels. If necessary, add ATF and
engine oil.
2. Drive vehicle for approximately 10 minutes or until ATF and
engine oil reach operating temperature.
3. Set parking brake and block wheels.
4. Install a tachometer where it can be seen by driver during test.
•It is good practice to mark the point of specified engine
rpm on indicator.
5. Start engine, apply foot brake, and place selector lever in “D”
position.
Fluid status Conceivable Cause Required Operation
Varnished (viscous
varnish state)Clutch, brake
scorchedReplace the ATF and check the A/T
main unit and the vehicle for mal-
functions (wire harnesses, cooler
pipes, etc.)
Milky white or
cloudyWater in the ATFReplace the ATF and check for plac-
es where water is getting in.
Large amount of
metal powder mixed
inUnusual wear of
sliding parts within
A/TReplace the ATF and check for im-
proper operation of the A/T.
SAT638A
ATF operating temperature: 50 - 80°C (122 - 176°F)
SAT647B
SAT513G
SAT775B
TROUBLE DIAGNOSIS
AT-51
< SERVICE INFORMATION >
D
E
F
G
H
I
J
K
L
MA
B
AT
N
O
P
Location of line pressure test ports are shown in the figure.
•Always replace pressure plugs as they are self-sealing bolts.
Line Pressure Test Procedure
1. Check ATF and engine oil levels. If necessary, add ATF or
engine oil.
2. Drive vehicle for approx. 10 minutes or until engine oil and ATF
reach operating temperature.
3. Install oil pressure gauge to corresponding line pressure test
port.
4. Set parking brake and block wheels.
5. Start engine and measure line pressure at idle and stall speed.
CAUTION:
• Keep the brake pedal pressed all the way down during
measurement.
• When measuring the line pressure at the stall speed, refer
to "STALL TEST".
SCIA7187E
ATF operating temperature: 50 - 80°C (122 -176°F)
SAT647B
SCIA6528J
SAT513G
SAT493G
AT-52
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
Line Pressure
Judgement of Line Pressure Test
Road TestINFOID:0000000001703183
DESCRIPTION
• The purpose of the test is to determine overall performance of A/T
and analyze causes of malfunctions.
• The road test consists of the following three parts:
1. Check before engine is started. Refer to AT- 5 3
.
2. Check at idle. Refer to AT- 5 3
.
3. Cruise test
• Inspection all the item from Part 1 to Part 3. Refer to AT- 5 5
,
AT- 5 8
and AT- 5 9 .
Engine speedLine pressure [kPa (kg/cm
2 , psi)]
D, 2nd and 1st positions R position
Idle speed 500 (5.1, 73) 778 (7.9, 113)
Stall speed 1,173 (12.0, 170) 1,825 (18.6, 265)
Judgement Suspected parts
At idleLine pressure is low in all positions. • Oil pump wear
• Control piston damage
• Pressure regulator valve or plug sticking
• Spring for pressure regulator valve damaged
• Fluid pressure leakage between oil strainer and pressure regulator valve
• Clogged strainer
Line pressure is low in particular posi-
tion.• Fluid pressure leakage between manual valve and particular clutch
• For example, line pressure is:
− Low in “R” and “1” positions, but
− Normal in “D”, and “2” positions.
Therefore, fluid leakage exists at or around low and reverse brake circuit.
Refer to AT- 1 9 , "
Shift Mechanism".
Line pressure is high. • Accelerator pedal position signal malfunction
• A/T fluid temperature sensor damaged
• Line pressure solenoid valve sticking
• Short circuit of line pressure solenoid valve circuit
• Pressure modifier valve sticking
• Pressure regulator valve or plug sticking
• Open in dropping resistor circuit
At stall
speedLine pressure is low. • Accelerator pedal position signal malfunction
• Line pressure solenoid valve sticking
• Short circuit of line pressure solenoid valve circuit
• Pressure regulator valve or plug sticking
• Pressure modifier valve sticking
• Pilot valve sticking
SAT786A